Floor in new extension possibly failing...

[spydie]

Had a nightmare extension last year (well, nightmare builders!!) and now worried the floor is failing.

Background, the screed failed in the kitchen and started cracking and crumbling in places whilst building work was still ongoing. Due to various c*ck ups by the builder, the extension was running hugely behind schedule and the screed was heavily trafficked. I also recall that the cellotex was cupping in places when the screed was laid and it was in those areas that the screed started falling apart and the u/f heating pipes started coming up.

Builder pulled a huge amount of it up and put down a latex compound and floor levelling compound over the rest (that looked like the Himalayas, it was THAT uneven).

We then went on to tile the floor ourselves. Fast forward 4 or 5 months, and in the exact same places that the screed started to break up initially, I've noticed a couple of the tiles seem to give a little crunch/crack when stepped on. The grout has started to crack around the edges of these tiles. No where else is this happening across 25sqm of floor. What are the chances it's the floor underneath failing again? And how on earth would we rectify this??

[another20]

We have endured something similar for years - individual tiles eventually cracked and we replaced them - but then the next tile would crack. People have suggested that the screed wasn't dried - so we can either dig it all up (knackering the v expensive tiles and UFH) and try to rectify and then lay tile again - or (which is what we are planning to do) lay a floating engineered wood floor over the lot....hoping that works.....